Abstract: This paper firstly reported the fermentation characteristics of immobilized yeast cells in soy sauce. The magnetic chitosan microspheres as a carrier of immobilized yeast cells. The consumption of reducing sugar was elected as the indexes in the same time, single factor experiment and response surface methodology of temperature, salt content and pH had been taken out to evaluate the impact of various levels. The result of response surface methodology showed that the best temperature, salt content and pH were 28.5℃, 8%, and 6.57, respectively. Calculation showed that the consumption of reducing sugar was 3.27g/mL. The immobilized yeast cells could increase the aroma effectively and improve the quality of soy sauce at the best fermentation conditions.